1. Field of the Invention
The present invention relates to clutch control apparatuses for vehicles, and more particularly, to a clutch control apparatus that includes an actuator for engaging and disengaging a clutch with two electric motors, that uses one or both of the electric motors as necessary, and that detects malfunctions of the electric motors and warns a driver.
2. Description of the Related Art
Recently, mechanical automatic transmissions that can perform automatic transmission using actuators attached to transmission gear mechanisms and clutch mechanisms similar to those of manual transmission vehicles have been developed and put to practical use mainly in large vehicles, such as trucks and busses.
In such a Vehicle, a friction clutch (hereafter simply called a clutch) disposed between an engine and a transmission and a gear shift mechanism of the transmission are activated by actuators that are respectively attached to the friction clutch and the gear shift mechanism.
The actuators may be electric actuators using electric motors, fluid-pressure actuators, such as pneumatic actuators using air cylinders and hydraulic actuators using hydraulic cylinders, etc. In particular, for the purpose of saving power and space, clutch engaging/disengaging actuators and gear-shift actuators using electric motors are suggested.
When an actuator is operated with a single electric motor, clutch control cannot be performed if the electric motor malfunctions and it becomes impossible to drive. In addition, the actuator cannot be operated with desirable responsiveness when only one electric motor is used.
In order to solve these problems, actuators using two or more electric motors as a power source are suggested.
When, for example, two electric motors are used as a power source and the two electric motors are always driven simultaneously, the actuator can be operated even if a malfunction, such as a self-rotation failure, occurs in one of electric motors. Therefore, the operation is continued without detecting the malfunction and it suddenly becomes impossible to drive when the other electric motor malfunctions. When only one of the electric motors is always driven to compensate for malfunctions, if the electric motor that is being driven malfunctions, the actuator is operated by driving the other electric motor. In this case, the clutch operation cannot be performed with desirable responsiveness when the vehicle starts moving or changes gears.